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mcgrew writes "The AP (via Yahoo) is reporting that Italian researchers can now cure blindness caused by chemical burns using the patient's own stem cells. 'The treatment worked completely in 82 of 107 eyes and partially in 14 others, with benefits lasting up to a decade so far. One man whose eyes were severely damaged more than 60 years ago now has near-normal vision.' Previously, this kind of injury needed either a corneal transplant or stem cells from someone else, both of which are plagued by problems with tissue rejection. Unfortunately, this only works for damaged corneas — so far."

I'm not a subject-matter expert; but, based on how badly a lot of injuries tend to heal in mature humans(I managed to grow a couple of arms and 10 fingers once, why not again if I happen to lose one or two?), I can only assume that evolutionary pressures imposed by some combination of the risk of cancer and the fact that, until the invention of modern medical care and life support systems, a quick-and-dirty healing job that turns into a ghastly mass of scar tissue is safer than a perfect regrowth that you w

I don't think that most higher organisms survive 'limb tearing off' events often enough for it to have a significant impact on evolution. Even having a finger torn off 20 thousand years ago would likely have killed you due to infection, and if it didn't, being short one finger wasn't going to be a huge problem for most things. Having an arm or leg torn off would almost certainly have killed you, on that basis that you'd lose a lot of blood, infection would kill you if the blood loss didn't, whatever tore yo

Isn't the bloodstream supposed to distribute stem cells and do repairs like this itself?

No. Stem cells in an adult appear to all be fate restricted to some degree. Embryonic stem cells are often called "pluripotent" meaning they can turn into any type of cell you need. Pluripotent stem cells disappear long before you're born, early on they start to specialize into three broad types of cells, and they get more and more specialized from then on, most appear to eventually get to the point where they'll make just one or two types of cells and that's it. Adult stem cell populations seem to be fate restricted as well. Stem cells in the later embryo and after birth are usually found in discrete niches tightly controlled, not just circulating. Some adult tissues appear to lack stem cells entirely too, I guess the cornea is one of those tissues.

One of the best characterized stem cell systems is in the intestines, you need to refresh your intestines fairly rapidly, its a tough environment for the cells making up your gut and they just don't last very long, getting sloughed every few days if I remember correctly. Those cells spring up from transient amplifying cells which divide very fast to make large numbers of intestine cells, but the transient amplifying cells come from stem cells located somewhere in the wall of the intestine. Last I heard, there was some controversy over which cells of the intestinal crypt were the actual stem cells, but they do appear to be in the walls of the intestine itself, not the bloodstream.

Furthermore, it appears that the intestinal stem cells only produce the lining of the intestine, they don't make the cornea, blood, nerves, bones, skin, etc. Maybe you could find a way to coax them into doing that, but as far as I know, that hasn't been shown yet.

Bottom line though, the stem cells that make up the intestine are in the intestine and make up only intestine. It appears most adult stem cells are similar: they make one type of cell from specific locations. Corneas do not appear to have a natural stem cell reservoir, so if you damage them you appear to be SOL as far as nature goes (I guess? Not really too familiar with the eye). In the present study, it looks like the researchers took stem cells from right around the cornea, not the bloodstream. Maybe cells from around the cornea naturally have the ability to differentiate into cornea type cells, I'd have to do some background reading.

But in general, no, there are not pluripotent stem cells floating around in your bloodstream. In cases where adult mice have had pluripotent stem cells injected into their bloodstream, they develop horrible tumors at those sites which are a complex mix of several different types of cells, a teratoma. I think the interpretation there is that stem cells generally need to be under tight control, which can't happen in the blood stream, or else you'll get them doing things you don't want them to do.

I'm waiting for one of these breakthroughs to happen in the US. It seems like every few months there's some leap in stem cell research. I always make it a point to look up where it happened. Never in America. It makes me sad to think while were taking over the world in search for oil, everyone else has learned to be civilized and aid each other.

Adult stem cells, which are found around the body, are different from embryonic stem cells, which come from human embryos and have stirred ethical concerns because removing the cells requires destroying the embryos.

how in hell there are stem cells around on an adult human? I didn't know that there are stem cells on adults. Isn't it true that people freeze umbilical cords in order to guarantee stem cells for the future?

The two broad types of mammalian stem cells are: embryonic stem cells that are isolated from the inner cell mass of blastocysts, and adult stem cells that are found in adult tissues. In a developing embryo, stem cells can differentiate into all of the specialized embryonic tissues. In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing specialized cells, but also maintain the normal turnover of regenerative organs, such as blood, skin, or intestinal tissues.

Could anyone elucidate me in the procedure for stem cell extraction? Where do they get those kind of cells on an adult human?

I think you mean "Could anyone elucidate the procedure" or "Could anyone educate me on the procedure". When elucidate [reference.com] is used with an object, that object is the thing being explained, not the person to whom it is being explained.
Oh. And by the way, I don't know anything about stem cells.

I believe it is well documented that some humans lose almost all ability to process vision information, if they go long enough without it. Surely this depends on the age at which vision is lost, and the duration of the blindness, but the problem of restoring vision processing, for those who have lost it, is significantly harder to solve.

The brain is probably the most incredible organ in the body, and yes, like your muscles if you don't use it it will atrophe, but it is amazingly resiliant so long as there's no actual damage to it.

After ten years of my eyes' focusing muscles not being used (in your forties the lens hardens and you need reading glasses) it only took a few months after getting my implant for the focusing muscles to work again. And the brain is the same way; you would have to learn to see again, but you would learn.

This article is long but fascinating - long story short, guy loses his vision as a young child (possibly the key point), regains it 45 years later, struggles very much to deal with sight for several years, but misses his past, sight-less life. He has a very hard time correlating objects' feel with their appearance, he has a hard time appreciating perspective, he can only navigate around his own h

Functional MRI scanning has shown that areas of the brain normally involved in vision processing has been reallocated in such individuals.

Coincidentally, I've just finished reading a great book on this very subject: "Crashing Through: A True Story of Risk, Adventure, and the Man Who Dared to See", by Robert Kurdson. He describes Mike May's frustrations with not being able to read or process shadows to determine 3D information after having his sight restored, decades after losing it due to corneal scarring

Um, this research was eligible for federal funding under President Bush and I assume it is still eligible for federal funding under Obama. The thing you seem to not have noticed is that this procedure works with adult stem cells, not embryonic stem cells.

No, the laser won't hurt your cornea (which is what this fixes) or lens, but it will burn you retina, and so far thay can't fix that (but I can see it happening not too long from now). You might be interested in this journal [slashdot.org] which actually has lasers in an eye, as well as a liquid nitrogen cooled cryotheraputic probe to the eye, as well as needles in the eye.

There are worse things than lasers. Like supercooled metal probes, needles, and nitrogen bubbles.

Stem cells are being shown to work in the few areas scientists are funded to study them. I dont think its a straw man argument to say that the religious zealots are stopping people with other conditions from being helped. If you want to split the generic/embryonic hairs here, that is your problem.

Many Christian's oppose the latter, and almost none is against the former.

I'm not even a Christian and I'm *&*#$# tired of the BS that comes from confusing the two positions. Seeing people attack straw men is annoying after the millionth time.

If you hate straw men, this is really the wrong place for you, it's kind of all we do here, be it on MS, stem cells, or car metaphors. You'll probably also want to avoid the "wizard of oz fanclub page."

Can we please just stick to arguing the unprovable question about whether all these breakthroughs with coerced non-embryonic stem cells would have happened if Bush hadn't enacted the Federal funding ban?

(though to be fair, those who argued that all useful stem cell research would go overseas were clearly wrong)

Is anyone working on treatments (stem cells, carbon nanotubes,magic fairy dust, whatever...) for repairing a wrinkled retina?(It detached, and the fine surgeon didn't get it reattached smoothly,so that eye is like trying to look through textured privacy glass.)

For the optical wizards out there, what would it take to makeeyeglasses that can correct extreme myopia without changingthe magnification? Would a multiple element lens be able todo this?